Scilab/C2/Plotting-2D-graphs/English-timed

Time	Narration
00:00	Welcome to the spoken tutorial on Plotting 2D graphs with Scilab.
00:04	Assuming that Scilab is installed on your computer, we will discuss plots in Scilab.
00:10	Scilab offers many ways to create and customize various types of 2D and 3D plots.
00:15	The several common charts Scilab can create are: x-y plots, contour plots, 3D plots, histograms, bar charts etc...
00:24	Now open your Scilab console window.
00:28	I will use Plotting.sce file to cut and paste the commands.
00:34	In order to plot, we need a set of points. Let us create a sequence of equally spaced points.
00:39	This can be done by the linspace command which creates a linearly equally spaced vector.
00:45	For Example,
00:48	x is a row vector with 5 points linearly equally spaced between 1 and 10.
00:57	Similarly y is a row vector with linearly equally spaced 5 points between 1 and 20.
01:08	More information on linspace can be obtained from the Help documentation.
01:14	We will now plot a graph with the arguments x and y using the plot function.
01:19	This is similar to the one used in matlab.
01:23	plot(x,y) creates a graph of x verses y as you see.
01:31	Notice that the Graphics window is labeled as '0'.
01:36	We will open another graphic window using the xset function.
01:41	I will close this.
01:43	Cut the xset function, paste in Scilab, hit Enter.
01:50	You will see a Graphic window number 1.
01:54	Note that two arguments are passed to this function namely the 'window' and 1.
02:03	The next graph will be plotted on this window.
02:06	For Scilab, plot2d is the native function used to plot 2d graphs.
02:14	plot2d command plots a graph of x verses y as you see.
02:26	Notice that there is a third argument called 'style'.
02:31	style argument is optional. It is used to customize the appearance of the plot.
02:36	For positive values of style, the curve is plain with different colours like green for 3 in our case.
02:44	The default value of style is 1.
02:46	Try plotting graphs for negative values and see the difference in appearance yourself.
02:51	Also we can set the start points and end points for x and y axes by passing the fourth argument.
02:57	It is called rect. As you see,
03:07	we have x axis starting from 1 to 10 and y axis from 1 to 20.
03:14	The order of argument in the rect command is xmin, ymin, xmax and ymax.
03:24	Let us now learn about title, axis and legends.
03:28	To configure labels to the axis and title to the plot we can use the commands title, xlabel and ylabel.
03:38	I will cut this set of commands and paste in the console. Hit Enter.
03:45	You will see that the graph has been labeled x to the x-axis, y to the y-axis and the title of the graph is 'My title'.
03:58	You may want to configure the title and axes of the plot in a single command instead of 3
04:04	For this purpose we use the xtitle command with all the 3 arguments.
04:11	I will cut this command, paste in scilab, Enter.
04:18	Now you see that the x axis label is X axis , Y axis and the title is 'My title'.
04:26	The clf() function that I am typing now, will clear the graphic window as you see.
04:36	It is useful while plotting different graphs on the same graphic window.
04:41	I will close this window.
04:44	Sometimes we need to compare two sets of data in the same plot, that is, one set of x data and two sets of y data.
04:51	Let us see an example for this, I will scroll down.
04:56	We will define the x-axis points in a row vector x using the linspace command.
05:03	Let us define a function
05:05	y1 = x square.
05:07	plot x verses y1.
05:10	Define another function y2 = 2 x square.
05:15	plot x verses y2.
05:17	We will also give label and title to our graph.
05:22	Notice that we have additionally passed ”o-” and ”+ -” commands to the plot function, to change the appearance of the curve.
05:33	These arguments are not a part of the plot2d function.
05:37	They can be used only with the plot function.
05:41	I will copy these set of commands and paste in the Scilab console.
05:49	You see the graph.
05:51	Wouldn't it be of great help to know which curve is associated with which function?
05:56	This can be achieved using the legend command as you see.
06:08	"o-" curve represents function y1=x square and "+-" curve represents function y2=2*x^2 (y2=2x square)
06:19	I will close this graphic window.
06:22	We will now discuss about plot2d demos and subplot function.
06:28	Scilab provides demos for all its major functions.
06:31	Demos of plot2d can be viewed through the demonstration tab.
06:39	Click on Graphics, click 2D and 3D plots and select a demo out of the various demos provided.
06:51	I will click on plot2d.
06:54	You will see the demo graph.
06:55	The code for this graph can also be seen by clicking on the view code button here.
07:02	This link does not open in Mac OS but it works in Windows and Linux.
07:07	Never the less in Mac the code can be viewed through the directory.
07:12	Let us go to the terminal.
07:15	Currently I am in 'demos' directory of Scilab 5.2 as shown.
07:21	The full path to this directory is shown here.
07:27	We will type ls to see the list of demos available, as you see here.
07:36	Then we will select the 2d_3d_plots directory and hit Enter.
07:46	Type ls again to see the various demo code available in the 'sce' files.
07:55	We will view the code for the demo which we have seen earlier.
08:00	Type more plot2d.dem.sce and hit Enter.
08:11	Here you will see the code for the demo graph of plot2d function.
08:18	I will close the terminal.
08:21	I will close the demo graph and the demo window.
08:26	Similarly you can go through the other demos and explore Scilab.
08:29	Let us now discuss about subplot function.
08:33	The subplot() function divides the graphics window into a matrix of sub-windows.
08:37	To explain this function we will use demos for plotting 2D graphs in Scilab.
08:43	For example, type plot2d in your console and see the demo plot for this function.
08:58	I will close this window.
09:00	The subplot command breaks the graphics window into a '2 by 2' matrix of sub-windows represented by the first two arguments in the subplot command.
09:10	The third argument denotes the current window in which the plot will be plotted.
09:15	I will execute this whole set of commands by copying it to the scilab console.
09:24	You can see 4 plots in a single plot window .
09:28	The plot obtained can be saved as an image on your computer.
09:32	Click on the graphic window, go to File menu, select Export to .
09:39	Give a suitable title to your plot.
09:50	Select a destination folder to save your file.
09:54	Select the file format in which you want your image to appear.
09:59	I will select the JPEG format and click Save.
10:05	Browse through the directory to open the image and verify yourself whether it has been saved or not.
10:11	This brings us to the end of this spoken tutorial on Plotting in Scilab.
10:15	There are many other functions in Scilab which will be covered in other spoken tutorials.
10:20	Keep watching the Scilab links.
10:22	Spoken Tutorials are part of the Talk to a Teacher project, supported by the National Mission on Education through ICT.
10:29	More information on the same is available on the following link.
10:32	Thanks for joining. Good bye.

Contributors and Content Editors

Gaurav, Krupali, PoojaMoolya, Sandhya.np14, Sneha